The objectives of this research are 1) to compare the efficacy and cost benefit of transtracheal (TT) and concealed nasal (CN) oxygen delivery to that of nasal cannula (NC) delivery and 2) to determine if the initial benefits of TT delivery are maintained with long- term (greater than or equal to 4 yr) use. Subjects will be patients diagnosed with COPD who require continuous home oxygen therapy and use a portable oxygen device. To test the first objective, a randomized design with two experimental groups and a control group will be used. Subjects will be randomized into 3 groups and receive either TT, CN or NC delivery. TT delivery will be accomplished using a catheter designed to deliver oxygen in this manner. For CN delivery, subjects will use eyeglass frames designed to disguise the oxygen tubing. Control group patients will receive oxygen via a NC. Dependent variables will be oxygen use (projected versus actual oxygen use), exercise tolerance (12 minute walk distance), respiratory symptoms (Bronchitis-Emphysema Symptom Checklist, Chronic Respiratory Disease Questionnaire), self-concept (Tennessee Self-Concept Scale) and participation in social and leisure activities (Katz Adjustment Scale). Measurements of 12 minute walk distance and scores on the Tennessee Self-Concept Scale and Katz Adjustment Scale will be obtained prior to group entry and treated as covariates, since prior data suggests great initial variability in regard to these measurements. Subjects in each group will be called weekly by nursing study personnel to document the type and frequency of problems associated with each mode of oxygen delivery and days of hospitalization for respiratory illness. In addition, morbidity and costs to implement the three methods of oxygen delivery will be determined. A one- group time-series design will be used to test the second objective. Subjects will be patients followed in the currently funded study. Dependent variables will be those measured in the current study. To evaluate mechanisms for improved exercise tolerance while using TT delivery, measurements will be made of inspiratory time (TI), expiratory time (TE), inspiratory time as a proportion of total respiratory cycle time (TI/TTOT), inspired tidal volume (VTI), inspired minute ventilation (VI), exhaled tidal volume (VTE) and exhaled minute ventilation (VE) at rest and during exercise while subjects receive gas flow at 0 and 6 LPM via the catheter. Consent will be obtained separately and subjects randomized to TT delivery not enrolled until completion of their prior 12 months of data collection.